Site To Site Extension Dialing

[Anonymous]

Would it be possible to set up site to site extension dialing in the following scenario? In a private MPLS network, where Site A can ping Site B: Site A has a Netvanta 7100 that has SIP coming in from the carrier..  It is using 4 digit extensions. Site B has a Total Access 908e. Site B has a Toshiba CIX670 PBX.  The Toshiba CIX670 is not SIP capable at this time.  The 908e receives SIP from the carrier; there is a PRI link between the 908e and the Toshiba CIX670.  Site B is using 3 digit extensions. Would it be possible to have a SIP trunk configured in Site A 7100 pointing to Site B 908e and vice versa and somehow have Site A be able to dial Site B extensions and Site B dial Site A extensions?

[jayh]

Yes. Build a SIP trunk between the two sites over the MPLS link. Work with your MPLS provider to tweak QoS as needed for call quality. Each end of the trunk points to the IP of the Adtran device at the other end. No need for registration.

To avoid dialplan conflict at site A, configure an unused leading digit (for example 7) to point to site B. Confugure a SIP grouped-trunk matching this and point it to site B. At site B accept the call and use match/substitute to strip the leading digit. The result should match the existing dialplan of the PRI. If the PRI expects more than 3 digits, then configure the match/substitute accordingly.

At site B, the Toshiba probably uses a leading 9 for outside calls as a trunk prefix.

Configure a second trunk with leading digit on the PBX, for example 8, with 4 digits to follow. PBX documentation may refer to this as a tie-line. Direct this to the PRI but don't strip the leading 8 as you do the 9. Set the SIP grouped-trunk at site B to accept 8XXXX and send to site A. At site A, use match/substitute to strip the leading 8 and it will match the extension dialplan.

Callers at site A dial 7XXX to ring site B. Callers at site B dial 8-XXXX to reach site A.

Substitute leading digits as needed if they conflict with existing dialplans.

[Anonymous]

Awesome.  Thx jayh.  I will attempt this.

[Anonymous]

Hi jayh, What if I already have SIP Trunks to other sites and are already using 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, 7xxx, 8xxx? BTW, Site B uses 2xx and 3xx.

[jayh]

You may have to get creative. Site A doesn't likely use 9 for outside so could use 9xxx or 1xxx.

If any of your other SIP trunk locations don't use X[2-3]XX you could share the first digit in your dialplan. For example if SIP trunk 5XXX connects to a site which uses only 55xx through 59xx then you could share that one. 5[5-9]XX goes to the existing, 5[2-3]XX goes to the new one.

In the worst case someone has to renumber. Painful but they'll get over it.

If you're really using 2xxx through 8xxx efficiently, that's somewhere close to 7,000 extensions and probably about time to go to a 5-digit dialplan at site A.

A thorough dialplan analysis should result in the ability to do some consolidation.

If you do have to renumber something, plan for growth so that you only need to do it once.

[Anonymous]

Site A uses 9-xxx-xxxx for dialing outside local numbers if that is what you mean.  Are we able to use 1xxx? I was under the impression that we could not use 1xxx.  We are using [2-8][2-3]XX at 7 locations.

[Anonymous]

Update: I managed to allocate 82XX and pointed to the 908e at Site B. The call makes it to the 908e on the new SIP trunk but that is as far as it goes.  The PRI Trunk Group has a permit template set to $.  Do I need to add 2XX to the permit template on the 908e PRI Trunk Group?  Attached is output from SIP All Debug on the 908e.

[Anonymous]

Update: The call was coming in on the right SIP trunk but was then attempting to go out T25 which is SIP to the carrier.  On T25 I did a deny template for 82XX and the call then routed to the PRI T01.  The call still did not complete.  I'm now getting the following... Retrieving Data................................................................................................... 03:50:14:139 VOICE.SUMMARY T02 is calling T01 (8243). 03:50:14:140 VOICE.SUMMARY DNIS Substitution: dialed number 8243 -> 243 03:50:14:385 VOICE.SUMMARY Call from T02 to T01 (8243) ended by T01: unallocated number

[jayh]

It sounds like you're really close. You just need to do a little tweaking toward the PRI trunk at site B. It probably doesn't know how to handle 8XXX.

Are you sending the PRI 3 digits?  If so, on that trunk do the following, assuming the PRI is T01:

voice trunk T01

match 82XX substitute 2XX

match 83XX substitute 3XX

If it expects 4 digits with a different leading digit (for example 5)

voice trunk T01

match 82XX substitute 52XX

match 83XX substitute 53XX

If it expects 7 digits (for example 555-02XX) then do the following:

voice trunk T01

match 82XX substitute 555-02XX

match 83XX substitute 555-03XX

You get the idea, you want to match/substitute so that the PRI sees a digit pattern matching what it sees from telco trunks for DID to extensions.

And, yes on  the grouped trunk for the PRI accept 82XX and 83XX cost 0 but it sounds like you did that.

Nope, you said that you denied it on the other SIP trunk. That works too, but in my opinion a specific permit where you want it to go is a better solution than denying it everywhere else. Either way works, but if you add more trunks things may break until you go around and deny what you don't want on each one. Easier to specifically permit and possibly more secure in some scenarios. Most specific match wins.

[jayh]

"debug voice verbose" at site B would be more useful than the SIP debug. We know the INVITE is getting there. 🙂

[Anonymous]

As I'm working through the GUI, when you say match/substitute, is this the same as adding a new DNIS substitution under Trunk Accounts > DNIS Tab in the 908e AOS GUI?

I asked the Toshiba system vendor if anything needed to be done on their end in order to reach extensions at site B coming in through the PRI and his reply was that he could create an  entry in the DID/DNIS table for 8243 and direct it to station 243 and that that should do it.  243 is the extension I'm currently testing with.

[jayh]

Yes, DNIS substitution on the trunk account associated with the PRI.

You really shouldn't have to have the Toshiba guy do any tweaks, assuming that the PRI is presently set up for extension dialing from other trunks (like from the PSTN).

On the PRI interface, how many digits are you sending to the PBX? It's in the GUI as a sub-link under physical interfaces, typically 4 or 7, could be 10.

If you're sending three digits, then the leading 8 will get stripped automatically and things should just work. If more than three, then you'll need to do a match-substitute on the trunk associated with the PRI, I think you said it's T01. It's under trunk accounts - DNIS substitution. You can make one entry for each 100 extensions. Match 82XX and substitute whatever is dialed to reach that extension from the PSTN, most likely the last 4 or last 7 digits of the actual phone number but end in XX. See my previous post for details and examples.

It's better to do the digit manipulation in the Adtran in my opinion, as the next PBX guy might not understand the whole thing and it could break something with the Toshiba dial plan. If you send the same digits that it's expecting from other trunks, it will just work.

You are very close to making this work, at least from A to B. From B to A you may need to get the Toshiba guy involved.

[Anonymous]

Yes, I'd prefer to have the least changes made on the Toshiba as possible.  On the 908e, Digits Transferred is set to All.  Previously, on a separate situation, I had asked our Toshiba vendor how many digits the PBX expects to receive and he told me it was 4.  I then checked with the Telco and they said they send 10 digits.  I expected that DNIS Substitution was taking place on the 908e but that is not the case.  I checked DNIS Substitution on the only two trunks we had configured in the 908e at the time and no Match/Substitution was taking place.  Since I already tried sending four digits before and that did not work I suppose I could try sending 10.  The thing is, I don't know what the leading digits should be.  I suppose that is something I need to ask the Toshiba vendor?

[jayh]

It is likely the full phone number of that extension including the area code. Do they have a block of 100 numbers where the last three digits are the extension? If so it should be match 82XX substitute NPA-NXX-X2XX where NPA-NXX-X are the area code, prefix, and next digit.

Look at the PRI interface in the TA900. how many digits is it configured to transfer?

Alternatively, ask the Toshiba guy.

Or, from the command line, turn on "debug isdn l2-format". Then dial the DID of an extension from your cell phone. You'll see a SETUP message. In that SETUP will be CALLED PARTY # and that will be exactly what is presented to the PBX. Tweak your DNIS substitute to match that format.

[Anonymous]

The Toshiba vendor went ahead and setup a DID for one of the extensions and I was able to reach that extension from Site A; now I need to provide him with DIDs for each of the extensions at Site B. Is it possible for me to assign 1[2-3]XX for this purpose.  I was under the impression that we could not assign the 1XXX extensions because they might be reserved for the system.  We use 9-XXX-XXXX 9-XXX-XXX-XXXX to make outside call but we are not using 1XXX anywhere on the Adtrans.  Is the 1XXX a viable option?

[jayh]

I'm not really a 7100 guy so can't comment on it. Try it and see if the configuration takes it, or perhaps someone else here can chime in. I can't think of a specific reason why it shouldn't work.

[jayh]

Were you able to get this working? How about in the other direction?

[Anonymous]

We are now able to dial all extensions at site B.  Site B cannot dial Site A extensions yet.  The Toshiba vendor said he would be creating a Dial 8 Group and would direct the traffic to the PRI but it did not work.  Staff at site B attempted to dial Intercom + 8  + 4 digit Ext as instructed by vendor but as soon as they dialed the second 8 they got a fast busy signal.  No digits came in on the PRI Trunk on the 908e.  i have not heard back from the vendor so we are still at it.

[jayh]

I'm not super familiar with Toshiba, but they probably shouldn't be dialing "Intercom", as that won't go outside of the PBX. Ask your Toshiba vendor to create a second trunk group just like the "dial 9" for outside line trunk group, but:

• No second dial tone after the 8 (or go ahead and provide it, your choice).
• Use the same PRI as the outgoing trunk.
• Don't "swallow" or suppress the 8, pass it through. You could swallow it and have theTA900 recognize just XXXX on the PRI as valid.
• Set the dial plan to recognize 8 + four digits as a complete pattern

This type of setup is typically called a "tie line" in the PBX world.

The users should be instructed to dial 8-XXXX for remote extensions just like they would dial 9-NXX-XXXX for a local call.

[Anonymous · Accepted solution]

After reading your post I asked staff at Site B to pickup a line same as when they will be dialing an outside call and dial Site A four digit extension.  To my surprise the PBX sent four digits over the PRI that I was able to process and route to the appropriate SIP Trunk.  So it is working Yay! Thx jayh, appreciate the help.